Tilting mechanisms are known in the prior art. They are used in "tilting trains". These are specially designed passenger trains, their design enabling their superstructure to be turned or "tilted" around its longitudinal axis relative to a bogie. This tilting process aims at compensating the horizontal acceleration acting upon the passengers in curves. Despite a considerable improvement of cruising comfort for the passengers, the curved tracks can be traveled much faster than allowed for normal trains by the EBO (German Rules for the Construction and Operation of rail vehicles), thus enabling the passengers to reach their destination much faster over winding railroad routes.
Such tilting mechanisms are subdivided into active and passive systems. Passive systems enable a tilting of the superstructure only as a result of centrifugal forces acting upon the superstructure. The tilting angle of such systems is, however, very limited, with maximum inclination angles of 1.2 to 3.5 degrees, depending on the design. Active systems make use of an adjusting means by which the tilting between the superstructure and the bogie can be controlled via a control loop, depending on the track curve and/or the velocity. These systems are generally suitable for a maximum inclination angle of approximately 8 degrees. This invention refers to such an active tilting mechanism.
In the known systems, the adjusting means either consists of a hydraulic servo cylinder or an electromechanical linear drive. The electromechanical linear drive, for example, is designed as a combination of an electromotor and a planet roller spindle. The adjusting means is located between the superstructure and the bogie.
It is known from the tilting trains in operation that an actuator force ranging from 8 to 10 tons is installed at each of the two bogies. Values this high are needed if the superstructure is to be held in its maximum excursion position of 8 degrees, since the center of gravity of the superstructure, in the case of large inclination angles, acts via a relatively large lever arm in the sense of a restoring torque. Forces this high are necessary to enable the superstructure to automatically return to its untilted initial position in case of a default of the tilting mechanism.
The design of the linear drive depends on the largest forces becoming active at a maximum angle of inclination. Furthermore, a relation between actuator force and the required torque at the motor exists for the known electromechanical actuators. In case of such a drive, it means that, for producing the necessary force, a current in the servo motor is necessary, its strength being also proportional to the angle of inclination. Since it is known that the stray power in a motor increases with the square of the engine current, this results in a considerably high stray power if the superstructure inclination is moving at high excursion angles.
This leads to the fact that the electromotor as well as the power electronics supplying it with electricity have to be designed for high levels of permanent power, naturally influencing the cost of acquisition of the mechanism. Furthermore, the dimensions of the drive have a major influence on the required space for installation. For larger drive motors, this installation space has to be sufficiently large.
Hence, it would be useful to create an actuator for the track curve-dependent control of a superstructure not characterized by the disadvantages described above with respect to the stray power occurring during operation at large inclination angles, and being additionally designed in a more compact and cost-efficient way.